# Yishto > Original bilingual engineering guides and independent products by Yishto. Offline examples are teaching data, not production measurements. Guide indexes link to Markdown versions with matching content, sources, and dates. ## Learning guides - [中文学习资料](https://yishto.com/learn/llms.txt): 中文系列、文章与 Markdown 入口。 - [English learning guides](https://yishto.com/en/learn/llms.txt): English paths, articles, and Markdown versions. ## About and products - [Author and editorial policy](https://yishto.com/about/): Yishto's editorial approach and privacy information. - [Products](https://yishto.com/products/): AI Nav City, Nav Tools, and Pixelprep.